Photopolymerizable compositions are being used for an increasing number of usages. For example this type of composition is now commercially used in resist formation, copying, printing, etc. Such compositions generally contain an ethylenically unsaturated compound or other type polymerizable compound, a photoinitiator or photoinitiator system and preferably a solvent-soluble or aqueous or alkaline soluble organic polymeric binder compound. Many of the known useful photopolymerizable compositions are limited in application because the initiators are not as active as desired and/or the initiators are activatable primarily in the ultraviolet region of the spectrum. Hexaarylbiimidazole compounds are good initiators of photopolymerization. To improve photospeed or to improve sensitivity in the visibile region of the spectrum, sensitizing amounts of arylidene aryl ketone compound of Dueber U.S. Pat. No. 4,162,162, N-alkylindolylidene or N-alkylbenzothiazolylidene alkanones of Dueber and Link U.S. Pat. No. 4,454,218, and constrained N-alkylamino aryl ketones of Anderson and Dueber U.S. application Ser. No. 645,115, filed Aug. 28, 1984 now U.S. Pat. No. 4,525,062, have been added to photopolymerizable compositions containing hexaarylbiimidazole compounds.
While the aforementioned compositions have either improved photospeed or provided improved sensitivity in the visible region of the spectrum, the known sensitizers are nonpolymeric compounds. It is desired to provide polymeric sensitizers which may improve adhesion in aqueous resists, restrict migration in multilayer films, or become incorporated into the photopolymer produced upon exposure.